In recent years, various proposals have been made with regard to optical scanning systems (and optical scanning devices) arranged as an optical deflector to perform sinusoidal vibration based on a resonance phenomenon.
In the optical deflectors using such resonance phenomenon, there is a certain resonance frequency determined as a targeted frequency of eigenmode relative to a desired driving frequency is determined (hereinafter, this resonance frequency will be referred to as “resonance frequency”). Several proposals have been made in regard to the method of manufacturing such optical deflectors using the resonance phenomenon.
Among them, Japanese Laid-Open Patent Application No. 2002-40355 discloses a technique concerning a method of manufacturing an oscillator device such as shown in FIG. 11.
In FIG. 11, there are mass loading members 1001 and 1002 which are formed at opposite ends of an oscillator having a reflection surface and an electric coil and supported by torsion springs around a torsion axis. When the resonance frequency of the oscillator is going to be adjusted, a weight (mass) is removed by irradiating a laser beam to the aforementioned mass loading members 1001 and 1002 to adjust the inertia moment weight, thereby to set the resonance frequency at a desired value.
Here, the amount of weight removal from the mass loading members 1001 and 1002 is determined based on the relationship between the number of laser irradiations and the amount of change of the resonance frequency having been inputted beforehand.